Miliolidid

Miliolidid is a subfamily of foraminifera, which are single-celled organisms belonging to the phylum Rhizaria. These marine protists are characterized by their distinctive calcareous shells, known as tests. Miliolidid tests are typically composed of calcium carbonate and exhibit a unique chamber arrangement. A common feature of miliolidids is their enrolled coiling pattern, often described as a series of chambers added in a spiral fashion. This coiling can be planispiral, streptospiral, or even triserial in some species, though the most characteristic is a bi-serial arrangement where chambers are added alternately on opposite sides of the test, giving the appearance of two rows of chambers.

The chambers of miliolidids are often agglutinated in a manner that creates a porcelain-like or glossy surface texture, a feature that distinguishes them from many other foraminiferan groups. Miliolidids are found in a wide range of marine environments, from shallow coastal waters to the deep sea, and are particularly abundant in tropical and subtropical regions. They are primarily benthic, meaning they live on the seafloor, but some species can be planktonic. Their diet consists mainly of diatoms, algae, and other microorganisms, which they capture using their pseudopodia, extensions of their cytoplasm. Fossil miliolidids are abundant in the fossil record, particularly in Cenozoic deposits, and are often used as paleoenvironmental indicators due to their sensitivity to salinity and temperature.